The document discusses the development and causes of cancer, emphasizing that it is a genetic disease characterized by uncontrolled cell division leading to malignant growths. It explains the classification of tumors into benign and malignant, with malignant tumors being dangerous due to their ability to invade and metastasize. Additionally, the document outlines the gradual accumulation of mutations in various genes that lead to cancer, detailing the stages of cancer development and the process of metastasis.

1. JABALPUR
PRESENTATION ON
DEVELPOMENT AND CAUSES OF CANCER
SUBMITTED BY:
Ambika Prajapati
M.Sc. Biotechnology III Semester

2. CANCER
Multicellular organisms coordinate their functions for the proper survival of the individual. Cells
send, receive and interpret an elaborate set of extracellular signals that serve as social
controls. Resting, growing dividing, differentiating and dying all depend on these signals.
Mutations tend to disrupt these social controls. Mutations give single cells a selective
advantage of more prolific growth and division as compared to other cells.
Cancer develops when an individual mutant clone of cells begins prospering at the expense of
its neighbours.
So, Cancer is a genetic disease characterized by uncontrolled division of abnormal cells
leading to a malignant and invasive growth or tumor.

3. TUMORS may be benign or malignant.
• BENIGN TUMORS: These, such as a common skin wart, remains confined
to their original location, neither invade surrounding normal tissue nor spread
to distant body sites.
• MALIGNANT TUMORS: These are capable of both invading surrounding
normal tissue and spreading throughout the body via the circulatory or
lymphatic systems (Metastasis).
Only malignant tumors are properly referred to as cancers, and it is their ability
to invade and metastasize that makes cancers so dangerous. Whereas benign
tumors can usually be removed surgically, the spread of malignant tumors to
distant body sites frequently makes them resistant to such localized treatment.

4. TUMOR CLASSIFICATION
Tumors are classified according to the type of cell from which they arise.
Most cancers fall into one of three main groups:
• CARCINOMAS : Carcinomas are malignancies of epithelial cells. These include
approximately 90% of human cancers like prostate cancer, breast cancer, lung cancer, and
colorectal cancer.
• SARCOMAS: Sarcomas are solid tumors of connective tissues, such as muscle, bone,
cartilage, and fibrous tissue.
• LEUKEMIAS and LYMPHOMAS: These account for approximately 8% of human
malignancies, arise from the blood-forming cells and from cells of the immune system,
respectively.

5. HOW DO NORMAL CELLS BECOME CANCEROUS?
• Development of cancer requires a gradual accumulation of mutations in a number of
different genes.
• Mutations in DNA sequences and abnormal epigenetic silencing of genes are responsible for
the development of most cancers.
• Mutations may be
• Inherited
• Due to errors in the replication of DNA
• Caused by Chemical carcinogens
• Due to radiations like UV and X rays
• Viral infections

6. GENETIC DRIVERS OF CANCER
The genetic changes that contribute cancer tend to affect three main types of genes:
Protooncogenes: code for cellular proteins which regulate normal cell growth and
differentiation.
Tumor Suppressor Genes: They are involved in controlling cell growth and division. Cells with
certain alteration in tumor suppressor genes may divide in an uncontrolled manner.
DNA Repair Genes: are involved in fixing damaged DNA. Cells with mutations in these genes
tend to develop additional mutations in other genes. Together, thess mutations may cause the
cells to become cancerous.

7. DEVELOPMENTAL STAGES OF A CANCER
1. DNA of a normal cell
This piece of DNA is an exact copy of the DNA from which it came. When the parent cell
divided to create two cells, the cell's DNA also divided, creating two identical copies of the
original DNA.
2. Mutation of DNA
Here is the same section of DNA but from another cell.
The DNA double helix has base pairs forming the rungs of the ladder like structure.
In this section of DNA, one of the base pairs is different from the original DNA. This DNA has
suffered a mutation, either through mis-copying (when its parent cell divided), or through the
damaging effects of exposure to radiation or a chemical carcinogen.
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8. 3. Genetically altered cell
Body cells replicate through mitosis, they respond to their surrounding cells and replicate only
to replace other cells. Sometimes a genetic mutation will cause a cell and its descendants to
reproduce even though replacement cells are not needed.
The DNA of the cell highlighted above has a mutation that causes the cell to replicate even
though this tissue doesn't need replacement cells at this time or at this place.
4. Spread and second mutation
The genetically altered cells have, over time, reproduced unchecked, crowding out the
surrounding normal cells. The growth may contain one million cells and be the size of a
pinhead. At this point the cells continue to look the same as the surrounding healthy cells.
After about a million divisions, there's a good chance that one of the new cells will have
mutated further. This cell, now carrying two mutant genes, could have an altered appearance
and be even more prone to reproduce unchecked.
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9. 5. Third mutation
Over time and after many cell divisions, a third mutation may arise. If the mutation
gives the cell some further advantage, that cell will grow more vigorously than its
predecessors and thus speed up the growth of the tumor.
6. Fourth mutation
The new type of cells grow rapidly, allowing for more opportunities for mutations. The
next mutation paves the way for the development of an even more aggressive cancer.
At this point the tumor is still contained.
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10. 7. Breaking through the membrane
The newer, wilder cells created by another mutation are able to push their way through the
epithelial tissue's basement membrane, which is a meshwork of protein that normally creates a
barrier. The invasive cells in this tumor are no longer contained.
At this point the cancer is still too small to be detected.
8.Angiogenesis
Often during the development of earlier stages of the tumor, or perhaps by the time the tumor
has broken through the basement membrane (as pictured above), angiogenesis takes place.
Angiogenesis is the recruitment of blood vessels from the network of neighboring vessels.
Without blood and the nutrients it carries, a tumour would be unable to continue growing. With
the new blood supply, however, the growth of the tumour accelerates; it soon contains
thousand million cells and, now the size of a small grape, is large enough to be detected as a
lump.
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11. 9.Invasion and dispersal
The tumour has now invaded the tissue beyond the basement membrane.
Individual cells from the tumour enter into the network of newly formed blood vessels, using
these vessels as highways by which they can move to other parts of the body. A tumour as
small as a gram can send out a million tumour cells into blood vessels a day.
10. TUMOUR CELLS TRAVEL - METASTASIS
What makes most tumours so lethal is their ability to metastasize -- that is, establish new
tumour sites at other locations throughout the body.
Secondary tumours.
Metastasis is now underway, as tumour cells from the original cancer growth travel throughout
the body. Most of these cells will die soon after entering the blood or lymph circulation.
11. METASTASIS
To form a secondary tumour, a tumour cell needs to leave the vessel system and invade
tissue. The cell must attach itself to a vessel's wall. Once this is done, it can work its way
through the vessel and enter the tissue.
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